1. Field of the Invention
The present invention relates to a method of manufacturing a field emission display, and more particularly to a method of packaging a field emission display.
2. Description of the Prior Art
A principle of a field emission device is as follows. Voltage is applied to a gate and an emitter tip so that electrons are emitted from the emitter tip. The electrons are accelerated by anode voltage and collided to an anode on which luminescent material is deposited. The luminescent material is excited by the electrons and emits light.
FIG. 1A is a cross sectional view for explaining a conventional field emission device. As shown in FIG. 1A, the field emission device has a lower substrate 100 on which an emitter tip 101 and a gate 102 are formed, and an upper substrate 120 under which anodes having luminescent materials are formed, with the lower and upper substrates 110 and 120 are combined by a spacer 130. The field emission device must be maintained in vacuum state.
FIGS. 2A to 2C are cross sectional views for explaining a conventional method of packaging a field emission display.
Referring to FIG. 2A, a lower substrate 110 on which a field emission device 100 is formed, and an upper substrate 120 having transparent electrodes 122, on which luminescent materials 121 are deposited, respectively, are combined by spacer 130 such as frit glass. An opening is formed in the lower substrate 110 and a glass tube 140 is attached to the lower substrate so that the opening is correspond to the glass tube 140. An exhaust process is performed to be exhaust air between the upper and lower substrates 120 and 110 through the tube 140, thereby maintaining vacuum degree of 1.times.10.sup.-7 Torr.
FIG. 2B is a cross sectional view to show a seal-off process. The lower part of the glass tube 140 is melted by a heater 150. If the glass tube melts some, the melt part of the glass tube 140 shrinks and is sealed off because of pressure difference by vacuum.
FIG. 2C is a cross sectional view in which the rest part of the glass tube 140 is cutted off.
However, vapor from the glass tube 140 is generated instantaneously and degrades internal vacuum at the very moment that the glass tube 140 melts in the vacuum packaging process as described above. Also, it is difficult to manufacture a field emission display with a flat board because of the long projected glass tube 140.